If you consider sites in the U.K. to be too formal have you considered the use of CLs or CSs?
There are some gems out there that are in beautiful locations and far from formal.
OK, they are not free like many Aires and Stellplatz, but may be worth a thought rather than taking a hit on the motorhome.
Good luck whatever you decide.
Yes, we have used CLs and CSs thanks, and they are nice and more casual, we're not looking for free stop-overs in particular, we just find in Europe the sites are generally more casual; it's much more a case of park how you want, just relax whereas so many places in the UK are park in a straight line, use the marker, loads of notices don't do this, that etc. We appreciate this suits many people so we're not knocking it, just not what we like. Also we're not the sort to sit on a campsite but we like to take off and explore the areas and in Europe parking a MoHo for a few hours is very often a welcoming experience whereas in the UK it's so often a nightmare. It's just personal preferences, but makes having a MoHo that is basically stuck in the UK not appropriate for us.